ENHANCED RNA EXPRESSION OF TISSUE INHIBITOR OF METALLOPROTEINASES-1 (TIMP-1) IN HUMAN BREAST-CANCER

Tissue inhibitor of metalloproteinases-1 (TIMP-1) is known to have at least 2 distinct types of activity, i.e., as a regulator of collagenol ytic activity, and erythroid potentiating activity (ERA). In this stud y, we examined the expression of TIMP-1 in human mammary carcinomas, n on-malignant breast tissues and benign breast tumors. A total of 53 sa mples were subjected to Northern-blot analysis, including 23 of primar y breast cancer, 26 of non-malignant breast tissues, and 4 of benign t umors. Of the 53 samples, 10 were paired malignant and non-malignant b reast-tissue samples from the same patient. TIMP-1 RNA expression was significantly higher in the malignant tumor tissues than in the non-ma lignant counterpart. Similar differences were observed in the level of TIMP-1 protein expression in the paired breast samples examined. More over, breast-cancer cell lines secreted larger amounts of TIMP-1 in vi tro than non-neoplastic breast epithelial lines. The up-regulation of TIMP-1 expression in breast cancer may suggest that TIMP-1 has an addi tional role to that of metalloproteinase inhibitor. (C) 1996 Wiley-Lis s, Inc.